This invention relates to a composite sheet comprising an elastically stretchable web and an inelastically stretchable web formed with inelastically stretchable continuous fibers and also to a process for making the composite sheet.
Japanese Patent Application Publication No. 1994-184897A describes elastically stretchable composite stock material obtained by a process comprising steps of stretching inelastic material to neck this material, bonding this material as it is necked to an elastically stretchable sheet which is under a tension at three or more non-linearly arranged regions and finally relieving the stretchable sheet of its tension. So far as the necked material is of fibrous nature, such process of prior art enables the necked material to form a plurality of gathers as the elastically stretchable sheet is relieved of its tension and thereby to convert a rubber-like touch peculiar to the surface of the elastically stretchable sheet to a comfortable cloth-like touch without deterioration of a desired stretchability of the elastically stretchable sheet.
According to this technique of prior art, the necked material is obtained by stretching, for example, a spun bond nonwoven fabric comprising thermoplastic synthetic fibers fused together in one direction. Of the fibers unevenly distributed in this nonwoven fabric, some are plastically deformed in the one direction and thereby actually stretched while the others are merely reoriented in the one direction as the nonwoven fabric is stretched in the one direction. The actual stretched fibers have their diameters reduced and the merely reoriented fibers maintain their initial diameters. Consequently, the elastically stretchable composite stock material obtained in this manner is disadvantageously accompanied with a remarkable unevenness of the fiber diameters. This may lead to the unevenness in touch as well as in appearance of the product.